Cancer is not a single disease, but encompasses well over a hundred distinct diseases of different organs. Normally cells divide only when additional cells are required for normal body function. However, at certain times the controls that regulate when a cell divides are lost. This results in accumulation of more and more cells without order. Eventually these cells grow into a mass and this is termed a 'tumor'. It is important to understand that not all tumors are cancer:

Benign tumors are NOT cancer. Benign tumors are only very rarely life-threatening. They do not spread and invade other tissues. Benign tumors can usually be removed and only infrequently grow back.

Borderline or Low Malignant Potential (LMP) tumors are a borderline form of cancer that may eventually spread and invade other tissues. This is a gray zone. Most of these tumors are benign but a few spread and progress. There are certain features that allow the pathologist to predict with some degree of confidence how one of these tumors will behave.

Malignant tumors are cancer. Malignant cancer will spread beyond the ovary, invading and damaging other organs of the body. The spread of cancer beyond its tissue of origin is called metastasis.

IntroductionSurface epithelial tumors account for ~60% of all ovarian neoplasms and 80-90% of malignant ovarian tumors. Serous tumors are the most common subtype. The generic term "ovarian cancer" usually refers to serous carcinoma, the most common type of malignant ovarian tumor in adults.

Surface epithelial neoplasms are also classified into subtypes based on the type of epithelial differentiation that is present in the tumor. The subtypes include serous, mucinous, endometrioid, clear cell, and transitional cell. The subtypes derive their names from the tissue that they most closely resemble:

Surface epithelial neoplasms of the ovary are classified based on the degree of epithelial proliferation and presence or absence of stromal invasion into morphologically benign and malignant subtypes. The pathology report contains the diagnosis.